Procedures of this kind and corresponding hole arrangements are known. By radially expanding a plug, usually made of a metal such as steel, a hole seal is produced which is intended to withstand extremely high pressures, e.g., far above 1,000 bars. The design of such a hole arrangement and the corresponding method for sealing a hole by inserting the plug and expanding it are very simple and widespread. The technique on which the present invention is based specieswise is based on sealing techniques using rubber-elastic or otherwise elastic sealing elements, which rest or are pressed against the hole wall within the scope of their elasticity. These sealing techniques are complicated because of the provision of elastic sealing rings, and it is therefore not possible to achieve seals that can withstand pressures of the order of magnitude mentioned above or can only be achieved by the additional effort of providing a plurality of sealing points in line with one another. A sealing technique of this kind, with sealing rings specifically provided for the purpose, is known, for example, from GB-A-2 020 774, and also essentially from DE-OS 2 706 337 and DE-PS 3 308 043, in which the seal is produced by means of a sealing ring. It is also known to seal holes by welding sealing plugs in place, as proposed, for example, by DE-OS 2 632 823. Another technique for sealing a hole using a rubber-elastic element is known from GB-PS 1,530,304. Other sealing techniques are shown in the following:
U.S. Pat. Nos. 4,301,629, 4,295,578, 4,282,982, 4,254,899, 4,227,625, 4,214,672, 4,083,468, 4,002,516, 3,979,013, 3,895,466, 3,828,968, 3, 144,162, Can.Pat. 865957, DE-PS 563 474, DE-OS 3 404 187, DE-AS 1 525 720, DE-PS 829 840, DE-OS 3 613 133, DE-PS 2 854 816, DE-OS 2 230 710.
Methods for tight sealing as well as correspondingly sealed holes, in which a plug is deformed plastically to produce a tight seat in the hole, i.e., at least similar to the above species, are known, for example, from CH-PS 508 828, CH-PS 503 923, CH-PS 506 732, DE-OS 2 457 407, DE-OS 2 744 501, DE-OS 2 632 823, DE-OS 2 508 269, U.S. Pat. Nos. 4,436,117, and 4,425,943, DE-GM 7 338 267. Thus, DE-OS 2 508 269 describes a method in which a ball is pressed into a hole, after which the latter is caulked.
In others of these proposals, a plug or plug-like element made of a relatively hard material such as a metal, is spread radially to produce the tight seat. Then there is the problem that in this procedure, while the tightness of the seal may be ensured, one cannot reliably prevent, especially under high pressure loads, the sealing elements from shifting axially in the hole even though it provides a seal. This risk is all the more insidious because it cannot be detected by a pressure drop, but only when the sealing element, propelled by the high pressure in the hole, is shot out like a projectile.